Two teenagers from one of New Jersey’s wealthiest suburbs were arrested this week for allegedly plotting to join ISIS and carry out mass killings of Jews. According to federal prosecutors, Tomas Kaan Jimenez-Guzel and Milo Sedarat, both 19, both from Montclair, had stockpiled weapons, posed with an ISIS flag, and fantasized online about attacks on Jewish communities. Sedarat, the son of a well-known poet, reportedly said he wanted to “execute 500 Jews” and “mow down” pro-Israel marchers in his hometown. Jimenez-Guzel — whose mother, Meral Guzel, works at the United Nations Women’s Entrepreneurship Program — posted photos of himself with...